The English name of the inverter is VFD or VVVF. It is a kind of electrical device that uses the inverter circuit to convert the constant frequency and constant voltage power into a variable frequency and voltage power source, and then controls the motor speed.
1
Structure of a typical inverter
The inverter is mainly composed of an operation display panel, a main circuit terminal block, a control terminal block, a control logic switching jumper, a PU interface, a current/voltage switch, a cooling fan, and an internal circuit.
1. Typical inverter operation display panel
2. Terminals for typical inverters
There are two types of terminals for the inverter: one is the main circuit terminal and the other is the control terminal. The main circuit terminal on the power supply side is mainly used to connect the three-phase power supply, and the main circuit terminal on the load side is mainly used to connect the motor.
3. The internal circuit of a typical inverter
The internal circuit of the frequency converter is mainly composed of a rectifier unit (power supply circuit board), a control unit (control circuit board), other units (communication circuit boards), high-capacity capacitors, and current transformers.
2
Use of typical frequency converters
Take the Emerson TD3000 inverter as an example
1. Operation display panel
2. Operation button
3. Menu function in parameter setting
4. Three levels of menu operation diagram
5. How to set the motor rated power parameters
6. Operation method and steps for setting motor comprehensive parameters
In addition to the above-mentioned operation of the rated power parameters and motor integrated parameters, the user password of the inverter, the auxiliary parameters of the inverter, the switch terminal parameters of the inverter, the function of copying the inverter parameters, and the parameters of the inverter stop display can also be used. Switch and other operations. The method of operation is basically the same as the two methods described above.
3
Inverter commissioning
After the installation and wiring of the inverter is completed, the inverter must be carefully debugged to ensure that the inverter parameter settings and the control system are correct before it can be put into use.
1. Check before power on
The check before the inverter is powered on mainly includes:
â—‡ Make sure that the power supply voltage is correct, and connect the circuit breaker in the input power supply circuit;
â—‡ Make sure that the inverter ground, power cable, motor cable, and control cable are connected correctly and reliably;
â—‡ Make sure that the inverter cooling and ventilation is smooth;
â—‡ Make sure the cover of the inverter is properly covered after the wiring is completed;
â—‡ It is determined that the current motor is in an idle state (motor and mechanical load are not connected).
In addition, in the inspection section before power-on, it is also important to clearly control the motor performance parameters before commissioning. The parameter information can be read on the nameplate of the controlled motor. This parameter information is an important reference in the parameter setting process of the frequency converter.
Close the circuit breaker and energize the inverter. Check whether the inverter has abnormal noise, smoke, odor, etc. Check the inverter's operation panel for fault alarm information and confirm that the power-on initialization status is normal. If there is any abnormality, disconnect the power immediately.
2. Set motor parameter information
Automatic tuning of the motor is a method by which the frequency converter automatically obtains accurate motor performance parameters. Under normal circumstances, before using the inverter to control the motor, before setting the inverter control mode, the nameplate parameter information of the motor should be entered accurately. The inverter can match the standard motor parameters according to the parameter information. However, if you want to obtain better control performance, after setting the motor parameter information, you can start the inverter to automatically tune the motor to obtain the exact parameters of the controlled motor. It should be noted that before the auto-tuning is performed, it must be ensured that the motor is in no-load and stall state.
3. Set the inverter parameter information
Correctly set the inverter's operation control parameters, ie set the function information such as control mode, frequency setting mode, frequency setting and operation selection under the “F0†parameter group.
Set the motor and frequency converter parameters according to the actual needs to set limit parameters, protection parameters and protection methods, such as the maximum frequency, upper limit frequency, lower limit frequency, motor overload protection, inverter overload protection, etc., the specific setting method can refer to the inverter Function parameter group, function code meaning.
4. Using the inverter's operation display panel for no-load debugging
After the parameter setting is completed, the direct debugging operation is performed with the inverter's operation display panel under the no-load status of the motor.
In the control relationship shown in the figure above, you can also perform jog control debugging training through the inverter's operation display panel, as shown in the figure below. In the debugging process, the power-on check and motor parameter setting are the same as the above-mentioned training. The difference is that the inverter parameter is set. In addition to setting the parameter information of the inverter, the inverter auxiliary parameter (F2) must also be set.
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